A newly formed special state committee investigating the George Washington Bridge scandal issued 20 subpoenas Thursday, including several to key staff members of New Jersey Gov. Chris Christie.

The legislative committee sent subpoenas to 17 individuals and three institutions. None was immediately named.

Assemblyman John Wisinewski, who is leading the investigation, said no names would be revealed until the recipients were officially served. That could happen Friday.

A New Jersey Senate committee is also investigating whether Christie's top advisers orchestrated or covered up lane closures near the bridge for political purposes.

Two Christie appointees to the Port Authority, which operates the bridge and other bi-state transportation entities, have already resigned in the wake of the uproar over the abrupt reduction from three access lanes to one onto the George Washington Bridge on Sept. 9.

The unannounced closure, which lasted four days, created huge traffic jams in Fort Lee, N.J., which is located at the base of the bridge, and raised speculation that it was retribution against the town's Democratic mayor for declining to endorse Christie for re-election in November.

Christie fired his deputy chief of staff, Bridget Anne Kelly, for allegedly lying to him about her involvement in the incident.

As a sign of increasing pressure, Christie announced Thursday that he has hired an outside law firm, including a former federal prosecutor, to head up an internal review of the case and to deal with the legislative inquiries and a probe by the U.S. attorney's office, the Asbury Park Press reports.

Christie said in a statement that hiring a law firm "will bring an outside, third-party perspective to the situation."

A member of the law firm, Randy Mastro, is a former assistant U.S. attorney in the southern district of New York who specializes in organized crime and racketeering cases.

In yet another development, Christie's former campaign manager, Bill Stepien, has hired an attorney,The (Bergen) Record reports.

The special committee created by the New Jersey Assembly on Thursday was given subpoena powers and has appointed its own former federal prosecutor, Reid Schar, to serve as special counsel. Schar successfully prosecuted former Illinois governor Rod Blagojevich, who is serving a 14-year sentence for corruption.

"I am confident these talented legislators have the backgrounds, temperaments and experience to conduct this inquiry in a bipartisan, professional and responsible manner," newly sworn-in Assembly Speaker Vincent Prieto, a Democrat, said after appointing the special committee.

Among those who could receive subpoenas are Port Authority Chairman David Samson, a Christie adviser; Christie aide Regina Egea, who is slated to become Christie's new chief of staff; and Michael Drewniak, the governor's chief spokesman.

The Senate committee that is running its own investigation will also subpoena documents and witnesses. "I'm not going to rule anybody out," said Senate Majority Leader Loretta Weinberg, who will chair the investigative committee in the upper house. "There are many other questions here."

Christie, who said he had no prior knowledge of the lane closures, said last week that he would cooperate "with all appropriate inquiries to ensure this breach of trust does not happen again."

David Wildstein and Bill Baroni, who claimed the closure was part of a traffic study, have already resigned from the Port Authority.

The role of Kelly, Christie's former deputy chief of staff, emerged in e-mails subpoenaed by a New Jersey transportation committee and released last week.

In one e-mail exchange between Kelly and Wildstein about two weeks before the lane closures, Kelly wrote: "Time for some traffic problems in Fort Lee."

To which Wildstein replied: "Got it."

Christie, in announcing Kelly's dismissal, said he did not quiz her about why she sent the directive, saying he did not want to be accused of interfering with a witness in the case.

The Port Authority, which operates the bridge at the heart of a New Jersey scandal, has informed a U.S. Senate committee inquiry that there is "zero evidence" that any legitimate traffic study was being carried out at the time that access lanes were closed.

The Port Authority statement came in response to an inquiry from Sen. Jay Rockefeller, a Democrat from West Virginia, who is chairman of the Commerce, Science and Transportation Committee.

As the scandal unfolded, aides to Christie attempted to explain the abrupt closures as part of a traffic study. As recently as last week, Christie — who said he had no prior knowledge of the lane closings — held out the prospect that a traffic study might have been involved, at least in part.

The George Washington Bridge, which runs between New Jersey and New York City, is at the center of a brewing scandal for New Jersey Gov. Chris Christie. E-mails and text messages suggest Christie's top aide (now ex-aide) and allies at the Port Authority engineered traffic jams in Fort Lee, N.J., last September to punish its Democratic mayor.